Heated molten metal pouring ladle

ABSTRACT

A substantially enclosed molten metal pouring vessel or ladle of the bottom pour type having a stopper rod extending vertically from the pouring spout in the base of the vessel, through the molten metal charge in the vessel and through the roof of the vessel to a stopper rod operating means located externally of the vessel. Means is provided to supply heat to the molten metal charge by heating the environment above the molten metal comprising the stopper rod having portions formed of a sufficiently high carbon content material to enable it to function as an electrical resistance heating element which is connected in a direct current electrical circuit by means of an electrical connection near the top of the rod externally of the ladle and an electrode located within the furnace wall in contact with the molten metal.

United States Patent Dershem et al.

HEATED MOLTEN METAL POURING LADLE Inventors: Thomas L. Dershem, Defiance;

Charles F. Renn, Bryan, both of Ohio General Motors Corporation, Detroit, Mich.

Filed: May 8, 1972 Appl. No.: 250,989'

Assignee:

References Cited UNITED STATES PATENTS 6/1957 Krall 13/33 X 4/1958 Hahn et al. 13/6 11/1959 Pinotti 13/6 Primary Examiner-R. N. Envall Attorney, Agent, or FirmPetcr P.. Kozak [57] ABSTRACT A substantially enclosed molten metal pouring vessel or ladle of the bottom pour type having a stopper rod extending vertically from the pouring spout in the base of the vessel, through the molten metal charge in the vessel and through the roof of the vessel to a stopper rod operating means located externally of the vessel. Means is provided to supply heat to the molten metal charge by heating the environment above the molten metal comprising the stopper rod having portions formed of a sufficiently high carbon content material to enable it to function as an electrical resistance heating element which is connected in a direct current electrical circuit by means of an electrical connection near the top of the rod externally of the ladle and an electrode located within the furnace wall in contact with the molten metal.

4 Claims, 2 Drawing Figures LOW VOLTAGE HlGH AMPERAGE D.C. SUPPLY PATENTEL HEY I 2 I974 LOW VOLTAGE HIGH AMPERAGE D.C. SUPPLY 1 HEATED MOLTEN METAL POURING LADLE BACKGROUND OF THE INVENTION This invention relates to molten metal pouring vessels and particularly to ladles of a substantially enclosed type having a bottom pour spout controlled by a stopper rod extending vertically through the molten metal.

In an effort to increase productivity it is becoming common foundry practice to automatically pour a relatively large number of molds sequentially from a relatively large ladle containing several tons of molten metal which are carried on a suitable conveyer. A suitable ladle for this purpose is one having an opening or spout at the bottom thereof and a stopper rod which extends through the cover of the ladle and through the molten metal to the pouring spout and is operated by suitable means located externally of the ladle.

In operation the conveyer and ladle are indexed so that a particular mold on the conveyer is brought into pouring position under the ladles spout for a predetermined time and the stopper rod opens the spout for a predetermined time sufficient to fill the mold with a predetermined charge of metal. This operating mechanism requires means whereby the stopper rod will open the spout progressively more as the metal head in the ladle drops to enablethe ladle to pour the predetermined charge in the predetermined time. One relatively simple and effective mechanism for this purpose is a conical spout seat cooperating with a conical stopper closure tip whereby the opening through the spout may be effectively varied in the manner of a needle valve. As is well known, accurate operation of a valve mechanism of this type requires that the spout or valve seat and the stopper rod tip surfaces be maintained clean and dimensionally accurate.

In pouring molten metal such as nodular or ductile iron containing small amounts of magnesium and sulphur, the stopper rod tip and spout seat surfaces tend to become fouled by a magnesium sulphate precipitate when the temperature of the molten metal falls below 2340F. This condition may, of course, be prevented by maintaining the molten metal at a temperature over 2340F.

SUMMARY OF THE INVENTION It is a principal object of this invention to provide relatively inexpensive and efficient means for controlling the temperature of the molten metal contained in a stopper rod controlled bottom pour ladle.

It is a more specific object of this invention to provide a heated environment over the molten metal within the ladle by forming the stopper rod of a relatively high carbon refractory material and imposing a low voltage, high amperage direct current across the portion of the stopper rod above the molten metal whereby the stopper rod functions as a resistance heating element and heats the environment over the molten metal.

These and other objects are accomplished by the provision of a substantially enclosed ladle having a pouring spout in the base thereof, a refractory stopper rod containing a relatively high carbon content vertically disposed within the ladle adapted to open and close the pouring spout. The stopper rod in a closure position extends vertically from the spout seat, through the cover of the ladle, and to a level externally of the ladle where it is attached to a suitable rod control mechanism. The portion of stopper rod external of the ladle is connected in an electrical low voltage, high amperage direct current circuit by a terminal connected directly thereto. The other electrical contact with the stopper rod is made through an electrode located in the wall of the ladle which under ladle operating conditions is in electrical contact with the molten metal and through the molten metal in physical contact with the stopper rod. In operation the portion of the stopper rod above the molten metal and up to the electrical connection above the ladle lid functions as a resistance heater which is operative to heat the environment above the molten metal and maintain the molten metal at a desired temperature.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial cross-sectional view in elevation of a substantially enclosed bottom pour vessel including a stopper rod for controlling the bottom pour spout, mechanism externally of the vessel for operating the stopper rod for vertical reciprocal movement and an electrical circuit with one terminal connected to the stop of the stopper rod and the other terminal connected to an electrode located near the bottom of the ladle.

FIG 2 is an enlarged fragmentary view in crosssection of the stopper rod shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawing illustrates a typical ladle to which the invention is applicable. It consists of a main body portion 10 and a lid portion 12. The main body portion consists of a steel shell 14 and an inner refractory lining 16 formed preferably of poured tabular alumina. The bottom pour spout 17 consists of a refractory nozzle 18 having an opening 20 and a conical seat 22 which is supported in the bottom of the vessel by a rammed alumina refractory plug 19. Incorporated in the wall of the bottom portion 10 of the ladle is an electrode 23 passing entirely through the wall of the ladle and forming a portion 24 of the interior surface of the ladle near to and preferably at the bottom thereof.

The top or lid portion 12 of the ladle similarly consists of a steel shell 26 and a poured tabular alumina refractory lining 28. The lid 12 includes a fill opening 30 and a closure 32 therefor. The ladle is provided with a slagging notch 33 through which slag is skimmed off the molten metal surface by means of a hoe-like device. Preferably the slagging notch is closed by a suitable refractory block (not shown) to prevent excessive heat losses therethrough when not in use. A stopper rod 34 is positioned vertically within the ladle and includes a conical tip 36 adapted for engagement with the valve seat 22 and a shaft portion 37 which extends vertically through the lid 12 through a suitable opening.

In accordance with the invention, the shaft portion 37 of the rod 34 is formed of a relatively high carbon refractory consisting, for example, of 25 percent by weight carbon, percent alumina and 5 percent binder such as sodium silicate or calcium aluminate. A suitable commercial material for this purpose is the Roto Rod material made by the Vesuvius Crucible Company.

The shaft portion 37 is threadably connected to a cylindrical steel support member 38 including an upper reduced diameter shaft portion 42 and a lower threaded reduced diameter portion 44 and further reduced diameter depending extension 46. The threaded portion 44, the depending portion 46 and the annular shoulder 48 are all preferably coated with a suitable ceramic layer 49 such as porcelain to provide electrical insulation between the steel support member 38 and the high carbon shaft portion 37.

The stopper rod is supported within the ladle for vertical reciprocal movement between spout open and spout closed end positions by means of a hydraulically operated device indicated generally at 50 pivotally connected to the shaft portion 42. The stopper rod operating mechanism 50 consists of support bracket 52 including the channel member 54 which are bolted to the steel shell of the ladle and 26 of the lid. The support bracket 52 carries a vertical bar 56 rigidly secured thereto and a hydraulic cylinder 58. The vertical support 56 is pivotally connected to and supports the horizontal bars 60 and 62 which in turn are pivotally connected to the L-shaped bar 64 including the rigid horizontal extension66 attached thereto. The bar 64 and the extension 66 are connected to the rod extension 42 through the partially-spherical bearing members 43 and 45 respectively and the stopper rod is held in a predetermined vertical position by the nut 47. The bar 60 is connected to the hydraulic cylinder 58 by means of the connecting rod 59.

It can be readily seen that a movement of the connecting rod 59 is operative to raise or lower the stopper rod in a true vertical alignment through the linkage described. This linkage arrangement is known in the art and is intended to illustrate a suitable mechanism for operating the stopper rod.

In accordance with this invention the upper end of the shaft 37 of the stopper rod external of the ladle is connected electrically to a source 68 of low voltage, high amperage direct current by means of a copper collar 70 and the cable 72 attached thereto. The portion of the stopper rod 37 within the ladle is connected to the'current source 68 through cable 71, the ground 73, the cable 74 connected to the electrode 23 and through the molten metal 75 contained in the vessel. Preferably the collar 70 is connected to the positive terminal of the current supply and the electrode 23 is connected to the negative terminal through ground. With this arrangement the stopper rod portion 37 is electrically insulated from the stopper rod operating mechanism 50 by means of the insulating layer 49 previously described. Of course, the collar 70 may be connected to the current source 68 through ground if desired and the polarity may be reversed.

The electrode 23 may conveniently be formed of the same refractory material as the rod portion 37 except that it is made sufficiently large so that it functions essentially as a conductor rather than a resistor.

In operation a relatively low voltage and high amperage are operative to provide the shaft 37 portion of the stopper rod above the molten metal with a resistance heating effect'sufficient to maintain the environment above the molten metal at a desired temperature level. Voltages in the vicinity of 40 to 60 and amperage in the vicinity of 10,000 may be used.

It will be apparent to those skilled in the art that although the invention has been described in terms of preferred embodiments other forms may be adopted within the scope of this invention.

LII

It is claimed:

1. A ladle comprising refractory walls including a base and a lid defining a substantially enclosed chamber for holding molten metal and having a bottom pour spout in said base,

a refractory stopper rod disposed within said chamber for partial immersion in said molten metal having a lower end for opening and closing said pouring spout and an upper end extending through said lid externally of said chamber and means for operating said stopper rod,

refractory electrode means sealingly extending through said ladle wall adapted for contacting the molten metal within said chamber,

electrical contact means associated with said electrode and said stopper rod externally of said chamber for connecting said stopper rod in an electrical circuit, at least the portion of said stopper rod above said molten metal level containing carbon in amounts so that the stopper rod above the molten metal level is operative to function as an electrical resistance heater in said electrical circuit.

2. A ladle comprising refractory walls including a base and a lid defining a substantially enclosed chamber for holding molten metal and having a bottom pour spout in said base,

a refractory stopper rod disposed within said chamber for partial immersion in said molten metal having a lower end adapted for opening and closing said spout and an upper end extending through said lid externally of chamber,

means externally of said chamber for reciprocably operating said stopper rod,

refractory electrode means sealingly extending through said ladle forming a portion of the said walls substantially at said base of said chamber so as to be in contact with molten metal in said chamber,

an electrical circuit including a direct current electrical energy source having one terminal connected to said stopper rod externally of said chamber and the other terminal connected to said electrode,

said stopper rod containing sufficient carbon to function as an electrical resistance heater when said circuit is energized and said chamber contains molten metal.

3. A ladle comprising refractory walls including a base and a lid defining a substantially enclosed chamber for holding molten metal and having a bottom pour spout in said base,

a refractory stopper rod disposed within said chamber for partial immersion in said molten metal having a lower end adapted for opening and closing said spout and an upper end extending through said lid externally of chamber,

means externally of said chamber for reciprocably operating said stopper rod,

electrical insulating means associated with said stopper rod for electrically insulating said operating means therefrom,

refractory electrode means sealingly extending through said ladle forming a portion of the said walls substantially at the base of said chamber so as to be in contact with molten metal in said chamber,

an electrical circuit including a direct current electrical energy source having one terminal connected to said stopper rod externally of said chamber and the other grounded terminal connected to said electrode,

said stopper rod containing sufficient carbon to function as an electrical resistance heater when said circuit is energized and said chamber contains molten metal.

4. A ladle comprising refractory walls including a base and a lid defining a substantially enclosed chamber for holding molten metal and having a bottom pour spout in said base,

a refractory stopper rod disposed within said chamber for partial immersion in said molten metal having a lower end adapted for opening and closing said spout and an upper end extending through said lid externally of chamber,

means externally of said chamber for reciprocably operating said stopper rod,

refractory electrode means sealingly extending through said ladle forming a portion of the said walls substantially at the base of said chamber so as to be in contact with molten metal in said chamber,

an electrical circuit including a 40 to 60 volt direct current electrical energy source having one terminal connected to said stopper rod externally of said chamber and the other terminal connected to said electrode,

said stopper rod containing about 25 percent by weight carbon to function as an electrical resistance heater when said circuit is energized and said chamber contains molten metal. 

1. A ladle comprising refractory walls including a base and a lid defining a substantially enclosed chamber for holding molten metal and having a bottom pour spout in said base, a refractory stopper rod disposed within said chamber for partial immersion in said molten metal having a lower end for opening and closing said pouring spout and an upper end extending through said lid externally of said chamber and means for operating said stopper rod, refractory electrode means sealingly extending through said ladle wall adapted for contacting the molten metal within saId chamber, electrical contact means associated with said electrode and said stopper rod externally of said chamber for connecting said stopper rod in an electrical circuit, at least the portion of said stopper rod above said molten metal level containing carbon in amounts so that the stopper rod above the molten metal level is operative to function as an electrical resistance heater in said electrical circuit.
 2. A ladle comprising refractory walls including a base and a lid defining a substantially enclosed chamber for holding molten metal and having a bottom pour spout in said base, a refractory stopper rod disposed within said chamber for partial immersion in said molten metal having a lower end adapted for opening and closing said spout and an upper end extending through said lid externally of chamber, means externally of said chamber for reciprocably operating said stopper rod, refractory electrode means sealingly extending through said ladle forming a portion of the said walls substantially at said base of said chamber so as to be in contact with molten metal in said chamber, an electrical circuit including a direct current electrical energy source having one terminal connected to said stopper rod externally of said chamber and the other terminal connected to said electrode, said stopper rod containing sufficient carbon to function as an electrical resistance heater when said circuit is energized and said chamber contains molten metal.
 3. A ladle comprising refractory walls including a base and a lid defining a substantially enclosed chamber for holding molten metal and having a bottom pour spout in said base, a refractory stopper rod disposed within said chamber for partial immersion in said molten metal having a lower end adapted for opening and closing said spout and an upper end extending through said lid externally of chamber, means externally of said chamber for reciprocably operating said stopper rod, electrical insulating means associated with said stopper rod for electrically insulating said operating means therefrom, refractory electrode means sealingly extending through said ladle forming a portion of the said walls substantially at the base of said chamber so as to be in contact with molten metal in said chamber, an electrical circuit including a direct current electrical energy source having one terminal connected to said stopper rod externally of said chamber and the other grounded terminal connected to said electrode, said stopper rod containing sufficient carbon to function as an electrical resistance heater when said circuit is energized and said chamber contains molten metal.
 4. A ladle comprising refractory walls including a base and a lid defining a substantially enclosed chamber for holding molten metal and having a bottom pour spout in said base, a refractory stopper rod disposed within said chamber for partial immersion in said molten metal having a lower end adapted for opening and closing said spout and an upper end extending through said lid externally of chamber, means externally of said chamber for reciprocably operating said stopper rod, refractory electrode means sealingly extending through said ladle forming a portion of the said walls substantially at the base of said chamber so as to be in contact with molten metal in said chamber, an electrical circuit including a 40 to 60 volt direct current electrical energy source having one terminal connected to said stopper rod externally of said chamber and the other terminal connected to said electrode, said stopper rod containing about 25 percent by weight carbon to function as an electrical resistance heater when said circuit is energized and said chamber contains molten metal. 